Quantitative measurements of manufactured products for quality control purposes can be difficult in high speed operations, such as when a target material is being conveyed at varying or high rates of speed, and/or the target material itself varies in one or more dimensions or characteristics. Often times, off-line testing is employed, such as complex laboratory testing and/or test methods, which can be time-consuming, and can result in significant amount of nonconforming product to be made before it is recognized that the process needs adjusting to make conforming product.
Online sensing and analysis offers the advantage of testing in real-time such that process parameters can be quickly and efficiently adjusted so that the target material is in conformance for a greater percentage of the manufacturing run, resulting in less waste and lower cost. Online sensing can be accomplished, for example, via laser spectroscopy. However, problems arise when the target material, i.e. the material to be measured, has motion relative to a laser focal point. U.S. Pat. No. 6,061,641 to Hahn is directed to an algorithm-based analysis of a spectral signal from a randomly-firing laser to determine whether the target was “hit” or not. Commercially available products are available that incorporate distance sensors for spectroscopic measurements. However, there remains a need for a laser-based spectroscopy system designed to solve the problem of performing laser-based spectroscopic measurements on a target item that has motion relative to a laser focal point or a measurement zone.